Visit http://en.m.wikipedia.beta.wmflabs.org/wiki/Selenium_page_issues_test_page in an incognito window
It appears that JS is not enabled, but in fact it seems mobiles modules are not getting loaded.
> mw.loader.getState( 'mobile.issues' )
registered
>mw.loader.getState( 'mobile.startup' )
registered
> mw.loader.getState( 'skins.minerva.scripts' )
registered
Note mobile.startup is a dependency of skins.minerva.scripts and skins.minerva.scripts
Looking at bottom of document in view source I see
mw.loader.load(["mediawiki.page.startup","mobile.head","mobile.site","ext.centralNotice.bannerController.mobiledevice","ext.centralNotice.bannerController.mobile","ext.centralNotice.bannerController.lib","ext.centralNotice.bannerChoiceData","ext.centralauth.centralautologin","ext.imageMetrics.head"]);
which includes skins.minerva.scripts ... why did it not load?